The present invention relates generally to determining the position of trains on a track and more specifically to determining characteristics of the train and/or track from the position of the train.
With the advent of train control systems, train scheduling systems and train separation, the location of a train on a particular track and its relationship to other trains and track structures is becoming increasingly important. Providing additional intelligence on the train as well as in central locations depend upon the accurate position of a train on a particular track. Global positioning systems (GPS) and other devices have been used to determine the position of the train. Data bases are provided on the locomotive as a point of comparison. Other input devices such as turn rate indicators, compasses, tachometers and odometers also provide additional information used to determine the position of the locomotive. Examples of such systems are illustrated in U.S. Pat. Nos. 5,129,605; 5,740,547; and 5,867,122. Due to the limit of accuracy of GPS data, U.S. Pat. No. 6,128,558 suggests using machine vision to detect relative locomotive position on a parallel track.
Another system which includes not only determining location but displaying control of a locomotive is described in U.S. Pat. No. 6,144,901 which is incorporated herein by reference. This system is directed to the LEADER System available from New York Air Brake Corporation in Watertown, N.Y.
The present invention makes use of the position data being determined on the train to determine characteristics of the train and/or the track. This is achieved by providing position determining devices at two or more locations along the train. The position of the locations are determined by the position determining devices. A processor determines the difference between the locations from the positions determined by the position determining devices and determines the characteristics of the train from the determined difference between the two locations.
For example, the locations of the position determining devices may be at the head end and rear end of the train. Thus, the differences of the two locations would determine the length of the train. The position is preferably taken when the train is traveling along a flat, straight track. This removes the curvature from the determination as well as any run-in or run-out which would lengthen or shorten the train if it is not flat.
The number of vehicles in the train are also determined and used to estimate the length of the train. The estimated length of the train is compared to the length of the train determined from the position determining devices and any discrepancies are determined. The discrepancies may then be reported. The number of vehicles in the train is determined either from a listing of the vehicles on the train or from the number of axles recorded in a hot box detection system on the train.
A plurality of lengths may be determined and the longest length selected as a length of the train. A plurality of sets of positions can be determined and the change of differences between the positions determined. This change of differences is used to determine a characteristic of the train. This will include run-in and run-out as well as in train forces.
The position determining devices can also determine the elevation of its location. The processor would then derive the grade of the track the train currently occupies from the determined difference of positions and elevations. This provides one track profile characteristic. The heading of each of the position determining devices will be used to derive a track profile with respect to curves.
Track structure information as a function of position and time is also provided to the processor. The track structure is entered at one of the positions of the position determining devices. This is correlated with the other information to provide additional information of the track profile. Track structures may be manually introduced while the other data from the position determining devices are automatically collected. Track structures include one or more of mileposts, bridges, tunnels, signals, crossings, overpasses, underpasses, siding, parallel tracks and whistle posts. The distance traveled along a track as a function of time is also used to derive the track profile.
The collecting of the data and the deriving of the track profile is performed as the vehicle travels the track. Thus, this not only provides information of the characteristics of the train, it also provides a track profile. If the track profile already exists, this method verifies, updates or corrects the pre-existing track profile in the processor. Also, using two or more positions determined by the position determining devices and correlating them to a track profile data base stored on the train, a more accurate determination of the location of the train on the track would result. Additional positioning locating devices may be provided along the train and provide position information to the processor. Preferably, the position determining devices are Global Positioning Systems.
When a train has passed over a switch in the track, determining two positions of the train before and after the switch and a comparison of these positions to the data base is used to determine which branch track the train is on. The two positions on each side of the switch may be determined simultaneously at two spaced portions of the train. Alternatively, the two positions are determined sequentially as the train passes from one side to the other side of the switch. An error is determined for the first position prior to the track by comparison to the first position of the data base and the same error is assumed for the second determined position past the track. This increases the accuracy of determining which branch the train is on.
Discrepancies can also be determined in the train consist definition as the train rolls across the track. This method includes storing a list on the train of the vehicles in the train. A report from the hot box detection system positioned along the track is stored on the train. The report includes the number of axles of the train monitored by the detection system. The list of cars is compared to the report for the number of axles to determine discrepancies. Any discrepancies are reported. The discrepancies would indicate that the stored list is inaccurate or the hot box detection system is faulty.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.